Yieldable pitman for power-hammers.



No. 739,992. r PATENTED SEPT. 29, 1903.

, F. I. DAVIDSON & G. T. STRITE. YIELDABLE PITMAN FOR POWER HAMMERS.

APPLICATION FILED MAY 13- 1902.

N0 MODEL.

ll/Mme sses.

the striking bar.

UNITED STA ES I Patented September 29, 1903.

PATENT O FICE.

FRANK F. DAVIDSON AND GEORGE T. STRITE, QF TAMA, If) W-A.,

Yl ELDABLE PITMAN FOR POWER-HAMMERS.

SPECIFICATION forming part of Letters'Patent No. 739,992, datedSeptember 29, 1903. Application filed May 13, 1902- Serial No. 107,208.(No model.)

To all whom it may concern:

Be it known that we, FRANK F. DAVIDSON and GEORGE T. STRITE, citizens ofthe United States, residing at Tama, in the county of Tama and State ofIowa, have invented certain newand useful Improvements in Yield-' ablePitmen for Power-Hammers, of which the following is a specification. I

This invention relates to that class of pitmen used for imparting acushioned reciprocating motion to a movable part-such, for example, asthe striking-bar of a power-hammer-and for the purposes of thisapplication the pitman is illustrated in connection with such hammer,and the entire mechanism will be fully hereinafter described.

In the drawings, Figure 1 is a side view in perspective of a hammerembodying our invention. Fig. 2 is a fragmentary view in perspectiveshowing the mounting of 4 the eccentric and the belt-tightener. Fig. 3is a central vertical section of the shackle conmeeting the eccentricwith the striking-bar. Fig. 4 is a sectional view showing theconstruction of the driving-pulley and the application of the brakethereto. Fig. 5 is a cross-section of the striking-bar through thepivotstud.

In the drawings, A is the base of the machine, composed of a pair ofstout timbers separated by a standard or post B at the back end and by ablock of corresponding thickness 0 at the front end. On the front end ofthe base is bolted the anvil-block D, adapted to take a suitable die F.To the upper end of the post is bolted an angle-block G, having bearingsG for the pivot H of the striking-bar I. The latter is a straight pieceof rectangular steel, and to its front end is bolted a die-block F. Thepivot of the striking-bar is shrunk in the bar and has trunnions journaled in the bearings of the angleblock. g

In suitable bearings J, secured to the base, is mounted a shaft K,provided with a drivin g-pulley L. Midway between the baseblocks aneccentric M is secured to the shaft.

To its upper strap is connected a rod N, threaded up a considerabledistance from the lower end and connecting about midway with a shacklehaving a pivotal connection with This shackle comprises a by bolts P.

having upwardly-extending arms IV.

pair of outwardly-curved arms 0 O, hinged to be secured frictionally tothe striking-bar The lower ends of the arms connect by. links Q Q with aknuckle R, and through this knuckle passes the eccentricrod and issecured thereto at any desired point by jam-nuts S S.

The upper un threaded end of the eccentric rod passes througha'guide-block T, provided with lateral bosses T to take the end ofcoiled springs U U. The other ends of the springs rest on similar bossesprojecting inwardly from the arms. the eccentric-rod up or downcompresses the springs until the force of the springs is sufficient toovercome the inertia of the strikingbar, when it partakes of themovement of the rod. The shackle thus forms a double-act ing and veryefficient cushion for the striking-bar, and in practice admits of nicemanipulation, either for light or heavy service. The lift of the hammermay be varied at pleasure by moving the jam-nuts up or down, and boththe position and the action of the hammer may be varied by shifting theclampplates on the striking-bar.

In bearings V Vis mounted a rock-shaft W,

Between two of these is mounted a tightenerpulley X. Two of the armsconnect by links Y Y with a foot-lever Y. To the shaft W is also hung abrake Z, linked to the foot-lever at Z and adapted to engage one of theflanges of the driving-pulley on the lower side. The counter movement ofthe foot-lever is secured by a spring Y drawing back the tightenerpulleyas soon as the foot is lifted and at the same time applying the brake.

Proper Weight is given to the driving-pulley to secure the desiredmomentum by fasten: ing to or forming ,on its sides heavy flanges L, theinner one of which forms a bearing for the brake. It will be seen thatthese flanges are made eccentric to the pulley, the longer radius of thebrake-flange being down when the striking-bar is up. By this arrangementthe brake catches the pulley at such a time asto stop the hammer withthe bar up. The other flange is set over oppositely, so as to balance.

It will be seen that a movement of Having thus described our invention,what we claim as new, and desire to secure by Letters Patent, is-

The combination in a pitman, of a shackle comprising a pair of armshinged together at one end and a connection thereof with thestriking-bar, a knuckle and pair of links connecting" the other ends ofthe arms, a guideblock, a pair of springs mounted between the 10guide-block and the arms, and a reciprocating rod mounted to slide alimited distance in said guide-block, and secured to the knuckle,substantially as described.

In testimony whereof we aifix our signatures in presence of twowitnesses.

FRANK F. DAVIDSON. GEORGE T. STRITE. Vitnesses:

NELSON E. KNIGHTS, JOHN W. ROBINSON.

